1. Field of the Invention
This invention relates to clocks employing pendulums and, more particularly, to a clock employing a physically detached pendulum which is magnetically levitated by means of feedback control.
2. Description of the Prior Art
Clocks which employ an oscillating pendulum physically attached to the clock mechanism, wherein the pendulum operates as the time-control element, are notoriously old. More recently, pendulum clocks have been developed wherein the time-control element comprises a quartz crystal and a physically attached oscillating pendulum is employed solely for ornamental purposes.
The art also includes mechanisms for magnetically levitating a ferromagnetic object (which may or may not be permanently magnetized), as well as controlling the spatial position of such a magnetically levitated object.
Further, the art includes a magnetically-levitated pendulum bob, disclosed in U.S. Pat. No. 2,566,221 of W. V. Lovell. Lovell describes an aluminum/copper ball which is levitated by means of magnetic induction. This ball exhibits translatory motion, which would permit the bob to be used as a pendulum. However, magnetic induction based on eddy currents and magnetic repulsion is electrically inefficient. The currents reported by Lovell are simply too high for use in making a practical clock pendulum which is safe for home use.
In addition, the art includes a pendulum clock in which the pendulum is a float disposed in a liquid, disclosed in U.S. Pat. No. 5,159,583 of Lee. This float is oscillated by means of an electromagnet.